For example, semiconductor devices such as diodes, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), etc., are used in power conversion circuits, etc. In these semiconductor devices, for example, a p-type semiconductor region is formed on a portion of an n−-type semiconductor region; and the breakdown voltage is obtained by a depletion layer spreading from the p-n junction surface into the n−-type semiconductor region.
However, in the case where the p-type semiconductor region is formed on the portion of the n−-type semiconductor region, the p-n junction surface includes a bent portion. The electric field concentrates at the bent portion of the p-n junction surface. Therefore, the breakdown voltage of the semiconductor device undesirably decreases due to the electric field concentration at the bend.
Accordingly, technology that can suppress the decrease of the breakdown voltage of the semiconductor device is desirable.